Example failure when TBR is missing: https://build.chromium.org/p/tryserver.infra/builders/Infra%20Presubmit/builds/2811/steps/presubmit/logs/stdio.

Example failure when CodeReview+2 from myself is missing:
https://chromium-review.googlesource.com/c/356430/2#message-e0ec47d0_4d2459b4

Ok, so one bit here is this: git cl upload should automatically set CodeReview+2 (self-lgtm) if user uses TBR. This would also fail immediately fail if user isn't a committer, which is nice. Filed  issue 626364  for that.

The second bit for PRESUBMIT, i don't have immediate idea. But it's totally valid point and thanks for feedback.

 Issue 624393  has been merged into this issue.

So, self-lgtm has been done. TBR hasn't and so this bug is still open. But we are already on par with rietveld.

Changed the subject to match how I think this should be fixed. Then PRESUBMIT could stop caring, because it knows Gerrit will take care of it. It'll also give us a better format for post-hoc auditing.

This can be implemented directly in gerrit, or as part of the rebase-always submit strategy.

Hm, not against TBRed-To and I'd vote for another plugin which adds extra lines.

However, what's the algorithm for determining who to "TBRed-To"? Given a CL with list of reviewers who didn't yet vote on CR+1, who will show up in TBRed-To? Everyone? 

Also, is this only if CL owner self-approved the CL?

Right.

If the CL has no approvals, it can't land anyway. That's fine.

If the CL is only self-approved, then:
1) If the CL has no reviewers other than the owner, reject submission; or
2) If the CL does have reviewers other than the owner, put them on the TBRed-To: line

 Issue 735351  has been merged into this issue.

Removing Milestone-Afterglow, as it has ceased to have meaning. More refined milestones may be added back in the near future.